This invention concerns a secured method for managing the operation of an apparatus by a user, which method is of the type enabling the operation of the apparatus only after detection by receiving means situated close to the apparatus, of a signal transmitted by portable transmitting means; the invention also concerns the hardware for the implementation of the method.
One already knows safety systems adapted on an apparatus which, to authorize the operation of this apparatus, involve the existence of a link between a transmitter carried by the user and a receiver provided close to said apparatus or on said apparatus.
For example, the document EP-0 319 428 describes an anti-theft safety device for vehicle comprising a portable transmitter which transmits a high frequency signal (HF), and a fixed receiver adapted for cutting off automatically the ignition circuit of the engine of the vehicle assembly, when the distance between the portable transmitter and the on-board received exceeds a certain value. Such a system stops the motor of the vehicle, in particular in case of theft, as soon as the vehicle moves away from the carrier of the transmitter.
The transmitter transmits a low power, encoded cyclic HF signal. When this signal is acknowledged and validated by the reception means, a relay or equivalent closes the ignition circuit of the engine to ensure its operation. When the reception system does not receive the HF signal transmitted any longer, the relay or equivalent cuts off the ignition circuit in order to stop the motor.
A time-delay circuit is provided to maintain the control of the relay for a duration greater than that intermediate two encoded sequences, in order to avoid any false interruption in case of interferences, or more generally in case of accidental loss of the signal.
However, if the duration of accidental loss of this signal is greater than the time-delay duration, the ignition circuit is automatically cut off by means of the relay and the motor of the vehicle does not operate any longer. This may cause sizeable malfunctions, and may even prove dangerous.
The object of this invention is to remedy this shortcoming.